How to Calculate Erythrocyte Volume

Erythrocytes, also known as red blood cells or RBCs, are the most populous in our blood. That is, they has a higher occurrence in our blood than any other one cell. Their main purpose is to bring oxygen to our body through the circulatory system. They are also responsible for the color of our blood. When a donation of plasma only is required, blood is extracted from the donor's body and put through a centrifuge. The RBC's are then returned to the body and the plasma is stored for donation.

Things You'll Need

• Patient
• Alcohol
• Needle and syringe
• Capillary tube
• Heparin
• Centrifuge
• Calculator

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Instructions

• 1

  Take blood from the person you want to test. First, sterilize the collection site with alcohol. Push the needle slowly and softly into the patient's arm. Using a syringe, remove 60 to 100 µL of blood.

• 2

  Put the sample in a capillary tube and add a few drops of heparin. Centrifuge it at 10,000 RPM for five minutes. You will see layers on the blood, the darkest of which is composed of red blood cells.

• 3

  Measure the volume of the darkest layer using the lines on the capillary tube.

• 4

  Divide the volume that you just measured by the total volume of the sample. Multiply the resulting number by 100. This is the percentage of RBCs in the sample and the percentage of RBCs in your blood. This number averages 48 percent for men and 38 percent for women. It usually reflects that the patient has around five to six million erythrocytes per cubic millimeter, if male, or four to five million erythrocytes per cubic millimeter, if female.